In the field of this invention it is known that it is desirable for wireless communications receiver to be capable of multi-mode operation (i.e., to be capable of operating in any one of a plurality of different modes, including both narrow- and wide-band modes—for example, 2G/2.5G/3G cellular modes (‘2G’, ‘3G’ and ‘2.5G’ referring respectively to cellular systems of second generation, third generation and intermediate therebetween) and GPS (Global Positioning by Satellite) mode).
In order to produce a multi-mode wireless communications receiver it would be possible to combine in one circuit separate receiver sections, each receiver section being dedicated to a limited number of modes. For example, a GSM receiver section could be combined with a WB-CDMA (WideBand-Code Division Multiple Access) receiver section to make a 3G/2G receiver). This approach has the advantage that would allow simultaneous multi-mode operation, but it has the disadvantage that it would not be cost-effective (it would contain many redundant blocks) for a limited flexibility (the resolution of pipelined A/D (Analog/Digital) converters usually used in a WB-CDMA receiver is difficult to extend beyond 10 bits) and would have a very high part count because the architectures of the individual receiver sections would be different (a superheterodyne receiver for one section, and a direct conversion receiver (DCR) for another section).